The wildfire that’s been raging in Yosemite National Park for 10 days came within two miles of a reservoir that supplies most of San Francisco’s water on Sunday, Reuters reports.

The “Rim Fire,” as it’s called, has already burned 134,000 acres, including 11 homes, and threatened both water and power supplies to the city, about 200 miles to the west. Nearly 3,000 firefighters on the front lines had about 7 percent of the fire contained Sunday.

The Hetch Hetchy Reservoir, which remained clear on Sunday despite threats of ash contamination, serves 85 percent of San Francisco with water. The city could draw on water from neighbors if the supply is compromised, according to a spokesman for the San Francisco Public Utilities Commission.

Officials are on the lookout for rapid shifts in wind that could threaten firefighters and fuel what is already the fastest-moving of 50 major wildfires in the drought-plagued western U.S. The scorching fire could send sparks more than a mile and a half out to ignite new hot spots, officials say.